Soil separator and sampler and method of sampling

ABSTRACT

A soil sampler includes a fluidized bed for receiving a soil sample. The fluidized bed may be in communication with a vacuum for drawing air through the fluidized bed and suspending particulate matter of the soil sample in the air. In a method of sampling, the air may be drawn across a filter, separating the particulate matter. Optionally, a baffle or a cyclone may be included within the fluidized bed for disentrainment, or dedusting, so only the finest particulate matter, including asbestos, will be trapped on the filter. The filter may be removable, and may be tested to determine the content of asbestos and other hazardous particulate matter in the soil sample.

CONTRACTUAL ORIGIN OF THE INVENTION

The United States Government has rights in the following inventionpursuant to Contract No. DE-AC07-05-ID14517 between the U.S. Departmentof Energy and Battelle Energy Alliance, LLC.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to soil samplers for use in determiningmaterials in soil, more particularly the presence of extremely fineparticulates, such as asbestos. The present invention is also directedto methods of testing a soil for asbestos content.

2. State of the Art

Asbestos exposure has been linked with various diseases, including lungcancer. Asbestos may be present naturally in soil, however with miningoperations, soil having higher asbestos concentrations may be exposed tothe air. Particularly in dry, windy conditions, asbestos exposure is aconcern for nearby residents. Cleanup for such a site can be expensive,as the quantity of soil needing removal and/or remediation may beimmense. It is necessary to identify sites asbestos contamination, aswell as identify the sites with the highest level asbestosconcentration.

Soil specimens may be taken quite readily; however, the samples must betested to determine the level of asbestos content. It may be lesscost-prohibitive to extract the asbestos from the soil sample on-site.The asbestos which has been extracted may then be transported and testedin a laboratory facility, rather than transporting the entire soilsample to a testing facility. One conventional method of extractingasbestos from the soil utilizes a glovebox. The soil sample may begathered in ajar, then the jar may be placed in the glovebox. Theglovebox may have a main chamber for handling and manipulating hazardousmaterials, and gloves, which may be accessed from the exterior of theglovebox, to enable a user to reach into the box and work with thehazardous materials inside, while separated from the hazardous materialsby the gloves. The jar containing the soil sample may be agitated andshaken by the user, then an air sample may be taken from the headspaceof the jar to be analyzed for asbestos.

However, conventional sample collection methods using a glovebox aretime intensive, requiring manual manipulation of the soil sample andmanual collection of the sampled air. In addition, the test results maybe inaccurate due to reliance upon manual agitation of the soil sample.Further, the recovery fraction of asbestos may be too small to provideaccurate test results.

Therefore it would be advantageous to provide method and a device forcollecting an asbestos sample from a soil specimen which is lessmanpower and time intensive, and provides a greater recovery fraction ofasbestos.

BRIEF SUMMARY OF THE INVENTION

One embodiment of the present invention includes a method of separatingparticulate matter from a soil sample. The method comprises introducingthe soil sample to a container, applying a vacuum to the container,fluidizing a plurality of particulates of the soil sample within thecontainer, drawing fluidizing air from the container across a filter;and collecting the fluidized particulate matter on the filter. The soilsample may be introduced to a funnel-shaped container, also known as aspouted fluidized bed or a cylindrical container, also known as acylindrical fluidized bed. A portion of the fluidized plurality ofparticulates may be disentrained, and remain within the container ratherthan being drawn across the filter. The largest particulates,particularly the dust, may be disentrained. A cyclone or a baffle may beprovided in the container or in the gas outlet from the container toenhance disentrainment. The vacuum may be a HEPA vacuum, and thefluidizing air may be exhausted through a HEPA filter, protectingpersonnel from exposure to hazardous particulates, particularlyasbestos, which may escape capture, remaining suspended in thefluidizing air beyond the collection filter.

In an alternative embodiment, the method and apparatus may be used tosample asbestos content of the soil without fluidizing the soil sample.For example, air may be passed through the soil sample withoutfluidizing the sample. Alternatively, air may be flowed through an inletto the container above the soil sample to allow sampling the air abovethe soil sample in the container.

Another embodiment of the present invention provides a soil separatorsystem comprising a fluidized bed configured for receiving a soil sampletherein, a removable collection filter in communication with thefluidized bed, and a HEPA vacuum system in communication with theremovable collection filter. A vacuum line may extend between thecollection filter and the vacuum system, and a flowmeter and a regulatorcontrolled by the flowmeter may be in fluid communication with thevacuum line.

The fluidized bed may comprise a spouted fluidized bed or cylindricalfluidized bed, and may include a baffle, a cyclone, or both suchcomponents, configured for disentrainment and disposed therein. Adistributor, for example, glass frit, a Teflon plug with one or moreholes, metal plate with one or more holes, or other porous materials,may be in fluid communication with an inlet of the fluidized bed todistribute the air therein. Optionally, a final HEPA filter may be incommunication with the HEPA vacuum to filter the exhaust air from thesystem for safety.

The soil separator system may be used to simultaneously test multiplesoil samples. A plurality of fluidized beds, each configured forreceiving a soil sample therein may be in communication with a removablecollection filter. The plurality of fluidized beds may be incommunication with the single HEPA vacuum through a manifold.

Yet another embodiment of the present invention is a disposablefluidized bed comprising a container having a removable lid andconfigured for receiving and fluidizing a soil sample therein, an inletat a first end of the container, an inlet cap for removably covering theinlet, an outlet at a second, opposing end of the container, and anoutlet cap for removably covering the outlet. The container may includea tapered portion and a cylindrical portion. A baffle, a cyclone or bothsuch components may be positioned within the container, in an inlet, orin an outlet and configured for disentrainment of a portion of suspendedparticulates therein. A distributor may be in communication with theinlet, configured for distributing the air within the fluidized bed.

Other features and advantages of the present invention will becomeapparent to those of skill in the art through consideration of theensuing description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

The foregoing and other advantages of the invention will become apparentupon reading the following detailed description and upon reference tothe drawings in which:

FIG. 1 shows a soil separator system of the present invention;

FIG. 2 shows a fluidized bed of the present invention; and

FIG. 3 shows another embodiment of a fluidized bed of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

A flow diagram of a soil separator system 100 of the present inventionis depicted in FIG. 1. The soil separator system 100 may be employed ina minimally equipped field laboratory to separate asbestos or othermaterials from a soil sample, or may be employed in a more completelyequipped production laboratory environment, after transportation of anintact soil sample. The soil separator system 100 may include afluidized bed 110 configured to fluidize a soil sample 105 therein. Avacuum pump or system 150 may be used to draw air through the fluidizedbed 110. The air may enter the fluidized bed 110 at an inlet 101, and adistributor 104 positioned adjacent the inlet is configured todistribute the air and retain the soil sample 105 within the fluidizedbed 110. The soil sample 105 may be mixed and fluidized within thefluidized bed 110. Fluidization may suspend particulates, includingasbestos particulates in the air. The air and the suspended particulatesmay be drawn through a collection filter 120, where the suspendedparticulates may collect, via vacuum line 155. The collection filter 120may be attached to the system 100 with a filter holder, so as to beremovable for testing. A flowmeter 130 may be in communication with aregulator 135 to control the suction applied to the fluidized bed 110.

The soil separator system 100 may include a single fluidized bed 110, ormay include a plurality of fluidized beds 110, 210, 310 (the number ofdepicted fluidized beds being nonlimiting and by way of example only) incommunication with a single vacuum 150. Each fluidized bed 110, 210, 310may have an associated filter 120, 220, 320 and an associated flowmeter130, 230, 330 and regulator 135, 235, 335. A manifold 170 may be used toconnect the plurality of fluidized beds 110, 210, 310 with the vacuumpump or system 150. The manifold 170 may include valves for controllingthe air flow from the plurality of fluidized beds 110, 210, 310, or theflow may be controlled with the flowmeters 130, 230, 330 and regulators135, 235, 335.

A main vacuum regulator 140 may control the flow of air through thesystem 100. The vacuum pump or system 150 may drive the flow, and may bea high efficiency particulate arresting (HEPA) vacuum pump or system,with all air flow exiting the system passing through a final filter 160,preferably a HEPA filter, prior to exiting the system 100. The finalfilter 160 may provide additional protection to personnel from exposureto any asbestos or other harmful particulate matter passing through thecollection filter 120. The vacuum pump or system 150 may draw airthrough the soil separator system 100 for a designated processing timeto enable thorough contact of the air flow and the soil sample 105, andcollection of asbestos on the collection filter 120. After thedesignated processing time has passed, the vacuum pump or system 150 maybe turned off, the collection filter 120 may be removed for analysis,and the container 106 of fluidized bed 110 may be disconnected from thevacuum line 155 (see FIG. 2). A cap (not shown) may be placed over theoutlet 109 and the inlet 101 of container 106, and the container 106,with the soil sample 105, may be disposed of, without any furtherpersonnel exposure to any potentially harmful material contained within.Such caps may include, a valve, a U-trap, a stopper, a screw-on cap, afriction fit cap, and the like. A U-trap or valve may be placed over theinlet 101 of container 106 to contain the sample during operation.

One embodiment of a fluidized bed 110 of the present invention isdepicted in FIG. 2. The fluidized bed 110 may comprise a funnel-shapedcontainer 106, with a tapered portion 106 a proximate the inlet 101 ofthe container 106. An upper portion 106 b may be cylindrical in shape.Optionally, the container 106 may have other configurations, for examplethe container 106 may be cylindrical or box-like. A fluidized bed 110having a funnel-shaped container 106, also known as a spouted fluidizedbed, may be used to fluidize a large range of particle sizes withminimal air flow, in comparison to the air flow required by fluidizedbeds having containers of other shapes. The entire soil sample 105 maybe circulated through a fluidizing zone within the container 106.

A distributor 104 may be disposed in the in the tapered portion 106 a ofthe container 106, adjacent the inlet 101 of the container 106. Adistributor may comprise a distributor plate, porous media such a glassfrit, or the like. The distributor is selected to allow a sufficient airflow rate into container 106 to fluidize the media without causingexcessive pressure drop. A distributor plate may be, for example, aTeflon plug or metal disk with a hole. In one embodiment the hole isapproximately a 10 mm hole. Alternatively the distributor plate may be aTeflon plug or metal disk with one or more smaller holes. Thedistributor may also be porous media such as glass frit or Dynapore™fluidizing media. Optionally, the distributor 104 may be disposedoutside the container 106, and air being drawn into the inlet 101 of thecontainer 106 will first pass through the distributor 104, as shown inFIG. 1. The porous media may comprise, for example, glass frit having apore size of about 150 to 220 microns and capable of allowing the airflow rate into container 106 required for fluidizing the sample withouthaving excessive pressure drop. The distributor 104 may be used todistribute the air being drawn into the container 106 and to retain thesample in container 106. A U-trap (not shown) may be added to the inletto container 106 to prevent solids from falling out of the vessel beforeair flow is started.

The soil sample 105 may be collected in the container 106, or the soilsample 105 may be collected in conventional containers, and transferredto the container 106 of the present invention. Optionally, collectingthe soil sample directly in the container 106 of the present inventionmay minimize personnel exposure to hazardous materials. The containerinlet 101 may have a cap to contain the soil sample. The cap may beremovable, and a distributor 104 may be attached. The inlet 101 maycomprise one opening, or a plurality of openings at one end of thecontainer 106. The openings may be sized to enable air flow into thecontainer 106, and retain the soil sample 105. Optionally, the inlet 101may have a mesh covering, a U-trap, or a valve, holding the soil sample105 in place, and providing an inlet for outside air. The container 106may comprise may be disposable after the soil sample 105 has beenfluidized, and the asbestos extracted. Such disposable containers 106may be, for example, plastic, glass, or aluminum.

Outside air may be drawn in through the inlet 101 of the container 106and into container 106 by suctioning from an outlet 109 of the container106. The moving air may be used to fluidize the soil 105 in thefluidized bed 100, as shown in FIG. 2. Fluidization may includesuspending particulates in an upward-flowing gas, for example, air, toform a gas-solid suspension. Vessels in which this suspension occurs arecalled fluidized beds because the suspended particles in the upward flowgas behave like a fluid. The velocity of the gas may determine the sizeof the particle which is transported with the gas out of the container106. At higher velocities, larger particulate matter may be transportedfrom the container 106. In one embodiment asbestos fibers that are about0.5 to about 20 microns long and about 0.5 to about 2 microns diameterare captured on the collection filter

A disentrainment portion 103 (see FIG. 2) of the container 106 may bethe portion of the fluidized bed 110 which provides an airspace abovethe soil sample 105. The disentrainment portion 103 may minimize dustcarryover to the collection filter 120. The heaviest particulates maydrop from the air to the bottom of the container 106, while the finestparticulate matter, including any asbestos, will remain suspended andpass to the collection filter 120. A cyclone 107 may be provided withinthe container 106 to dedust the air. The cyclone 107 is also known as acyclone precipitator or a centrifugal separator. The cyclone 107 may beused to direct the fluidized air in a circular flow, and the heavierparticulate matter may drop from the circulating fluidized air back tothe container. The asbestos and the smallest particulate matter willremain fluidized, and continue with the flow of air through the outlet109 of the container 106 to the vacuum line 155 leading to thecollection filter 120. The vacuum line 155 may comprise, by way ofexample, plastic, rubber, glass, or metal tubing. The tubing may beflexible or rigid. Additional vacuum lines may lead from the collectionfilter 120 to the regulator 135, the flowmeter 130 the vacuum regulator140, the vacuum pump or system 150, and the final filter 160.

In certain embodiments, the container 106 may include second inlet 101 blocated above the level of the soil sample. This inlet 101 b allows airto be drawn in to sample the air above the soil sample without flowingair through the sample. In such embodiments, the air above the samplemay be filtered to collect airborne particles without disturbing orfluidizing the soil sample. The purpose of this option is to reduce theamount of asbestos entrained and collected on the filter 120 to simulateasbestos release from low soil disturbance.

In other embodiments, an air flow rate less than that required tofluidize the sample may be flowed through either inlet 101, 101 b. Suchlower flow rate may be used such that the bed is not fluidized and lessparticulate matter is entrained and collected on the filter. The purposeof this option is to reduce the amount of asbestos entrained andcollected on the filter 120 to simulate asbestos release from moderatesoil disturbance.

FIG. 3 depicts another embodiment of a fluidized bed 410 of the presentinvention, having a container 406. The fluidized bed 410 additionallyincludes a baffle 408 to separate dust particles and asbestos, enablingthe asbestos to pass through the container outlet 409 to the collectionfilter 120, and minimize the dust collected on the collection filter120. The baffle 408 may be positioned to disturb the flow of air withinthe container 406, enabling the largest particulates to drop into thecontainer 406, and asbestos and other smaller particulates may continuewith the flow of air, through the outlet 409 of the container 406. Thecontainer 406 includes a tapered, such as substantially conical, lowerportion 406 a. Each wall of the tapered portion 406 a may extend offfrom vertical at an angle a. The angle a may be, for example, 30°, suchthat the bottom of the container defines an included angle of 60°. Theheight hi of the tapered portion 406 a may be, for example, betweenabout 15 cm and about 20 cm, about 17.1 cm being a currently preferredheight. The overall height h₂ of the container 406 may be between about17 cm and about 22 cm, about 19.6 cm being a currently preferred height.An upper portion 406 b of container 406 may be cylindrical in shape,with a height h₃, the difference between the overall height h₂ and theheight hi of the tapered portion 406 a. The diameter d of the upperportion 406 b may be between about 17 cm and about 22 cm, about 19.8 cmbeing currently preferred. The size and dimensions of the fluidized bedcan be changed to accommodate larger or smaller sample sizes.

A soil sample 405 may be disposed in the container 406. For example, a15 gram soil sample 405 may occupy container 406 to a height h_(s) ofabout 3.6 cm. Thus, with a 15 gram soil sample 405 there is a largedisentrainment section 403 within the fluidized bed 410. The relativelylarge diameter d of the cylindrical upper portion 406 b enables thesuperficial velocity of the suspended matter to be reduced. Thus,disentrainment of particulate material will occur, and carryover ofunwanted material will be minimized. Asbestos may remain suspended, andpass through outlet 409 to the collection filter 120.

The sizes of container 406 should not be construed as limiting the scopeof the present invention, but merely as providing specifics of someexemplary embodiments. The container 406 may be much larger, andconfigured to receive a larger quantity of soil therein. The soilseparator system 100 may thus be useful for soil remediation, removingunwanted asbestos and other fine particulate contaminants from soil. Therecovery fraction of asbestos using the soil separator system 100 of thepresent invention may be greater than the recovery fraction obtainedusing conventional methods.

The container 406 may include a removable lid 415 to facilitateplacement of a soil sample 405 within container 406. The lid 415 may beflat or domed in shape, and attached to the upper, cylindrical portion406 b of the container 416. The lid 415 may be attached with a threadedfitting, an interference fit, or any other suitable attachment method. Agasket or other seal element may, optionally be used to provide a sealagainst air leakage between removable lid 415 and upper, cylindricalportion 406 b. A vacuum line 455 may be removably attached to the lid415 at the container opening 409, or the vacuum line 455 may bepermanently attached or integrally formed with the lid 415. The size ofthe vacuum line may vary depending on the size of the container 406. Oneembodiment of the present invention includes a vacuum line 455 with adiameter of between about 5 mm and about 8 mm. The vacuum line 455 maybe sealed with an outlet cap 457 when the vacuum line is not incommunication with the collection filter 120. Alternatively, the vacuumline 455 may be removable at the container opening 409, and the outletcap 457 may be placed thereon. An inlet cap 407 may be used to cover thecontainer inlet 401 when the vacuum is not being applied across thefluidized bed 410. Alternatively, the inlet 401 and the outlet 409 maybe sealed by disposing plugs within the openings.

The inlet cap 407 and the outlet cap 457 may be useful to retain thesoil sample 405 within the container 406, for example if the soil sample405 will be transported before extracting the particulate matter, or forsafe disposal of the container 406 and soil sample 405. FIG. 3 alsodepicts an optional U-trap added to the inlet of conical section 406 ato prevent the soil sample from draining out of container 406.

The collection filter 120 may comprise, for example a mixed celluloseester filter with a 0.45 micron pore size as is used for NationalInstitute for Occupational Safety and Health method 7400 for collectingasbestos samples from air. Filters for sampling asbestos typically havea pore size of about 0.45 micron. One suitable filter is available fromthe Millipore Corporation of Billerica, MA. The collection filter 120may be examined, for example in an off-site laboratory, to determine thetype and concentration of particles trapped on the filter media. Theasbestos content of a soil sample 105, 405 may thus be determined.

Although the foregoing description contains many specifics, these shouldnot be construed as limiting the scope of the present invention, butmerely as providing illustrations of some exemplary embodiments.Similarly, other embodiments of the invention may be devised that do notdepart from the spirit or scope of the present invention. Features fromdifferent embodiments may be employed in combination. The scope of theinvention is, therefore, indicated and limited only by the appendedclaims and their legal equivalents, rather than by the foregoingdescription. All additions, deletions, and modifications to theinvention, as disclosed herein, which fall within the meaning and scopeof the claims are to be embraced thereby.

1. A method of separating particulate matter from a soil sample,comprising: introducing the soil sample to a container; applying avacuum to the container to draw a gas into the container; fluidizingparticulates of the soil sample within the container using flow of thedrawn gas; drawing gas containing at least some of the fluidizedparticulates from the container across a filter; and collecting the atleast some fluidized particulates on the filter.
 2. The method of claim1, wherein introducing the soil sample to a container comprisesintroducing the soil sample to a funnel-shaped container.
 3. The methodof claim 1, further comprising disentraining a portion of the fluidizedplurality of particulates, to cause the disentrained portion of theplurality of particulates to remain within the container.
 4. The methodof claim 3, wherein disentraining a portion of the fluidized pluralityof particulates comprises creating a cyclonic gas flow path in thecontainer.
 5. The method of claim 3, wherein disentraining a portion ofthe fluidized plurality of particulates comprises using at least onebaffle in the container.
 6. The method of claim 1, further comprisingexhausting the fluidizing gas through a HEPA filter.
 7. A disposablefluidized bed, comprising: a container having a removable lid, thecontainer comprising: a conical portion configured for receiving andfluidizing a soil sample therein; and a cylindrical portion having adiameter substantially similar to the diameter of the largestdiametrical dimension of the conical portion; an inlet at a first end ofthe conical portion of the container; an inlet cap for removablycovering the inlet; an outlet in the cylindrical portion of thecontainer, at a second, opposing end of the container; and an outlet capfor removably covering the outlet.
 8. The disposable fluidized bed ofclaim 7, wherein the included angle of the conical portion is about 60degrees.
 9. The disposable fluidized bed of claim 7, further comprisinga baffle positioned within the container and configured fordisentrainment of a portion of suspended particulates therein.
 10. Thedisposable fluidized bed of claim 7, further comprising a cyclonepositioned within the container and configured for disentrainment of aportion of suspended particulates therein.
 11. The disposable fluidizedbed of claim 7, further comprising a distributor in communication withthe inlet.
 12. The disposable fluidized bed of claim 7, the containerfurther comprising a second inlet position above an anticipate level ofthe soil sample.
 13. The disposable fluidized bed of claim 7, furthercomprising a distributor in fluid communication with the inlet fordistributing a flowing gas in the soil sample.
 14. The disposablefluidized bed of claim 7, further comprising a U-trap in fluidcommunication with the inlet.
 15. A soil separator system, comprising:at least one fluidized bed configured for receiving a soil sampletherein; a removable collection filter in communication with thefluidized bed; and a HEPA vacuum apparatus in communication with theremovable collection filter.
 16. The soil separator system of claim 15,wherein the at least one fluidized bed comprises a plurality offluidized beds, and further comprising: a manifold in communication witha plurality of fluidized beds and the HEPA vacuum apparatus; a pluralityof removable collection filters in communication with a fluidized bed ofthe plurality and the manifold.
 17. The soil separator system of claim15, further comprising: a vacuum line extending between the collectionfilter and the vacuum apparatus; a flowmeter in fluid communication withthe vacuum line; and a regulator controlled by the flowmeter and influid communication with the vacuum line.
 18. The soil separator systemof claim 15, wherein the at least one fluidized bed comprises a spoutedfluidized bed.
 19. The soil separator system of claim 15, wherein the atleast one fluidized bed further includes a baffle disposed therein. 20.The soil separator system of claim 15, wherein the at least onefluidized bed further includes a cyclone disposed therein.
 21. The soilseparator system of claim 15, wherein the at least one fluidized bedfurther includes a porous media in fluid communication with an inlet ofthe fluidized bed.
 22. The soil separator system of claim 21, whereinthe porous media comprises glass frit.
 23. The soil separator system ofclaim 22, wherein the porous media is disposed either within the atleast one fluidized bed or within a distributor in communication withthe inlet thereof.
 24. The soil separator system of claim 15, furthercomprising a final HEPA filter in communication with the HEPA vacuumapparatus.
 25. A method of separating particulate matter from a soilsample, comprising: introducing the soil sample to a container; applyinga vacuum to the container to draw a gas into the container; flowing thedrawn gas through unfluidized particles of the soil sample; drawing gascontaining at least some of the particles of the soil sampleparticulates from the container across a filter; and collecting the atleast some of the particles of the soil sample particulates on thefilter.
 26. The method of claim 25, further comprising exhausting thedrawn gas through a HEPA filter.
 27. A method of separating particulatematter from a soil sample, comprising: introducing the soil sample to acontainer; applying a vacuum to the container to draw a gas into thecontainer; flowing the drawn gas above unfluidized particles of the soilsample; drawing gas containing at least some of the particles of thesoil sample particulates from the container across a filter; andcollecting the at least some of the particles of the soil sampleparticulates on the filter.
 28. The method of claim 27, furthercomprising exhausting the drawn gas through a HEPA filter.